1. Field of the Invention
The present invention relates to a sealing apparatus applicable for a shaft sealing portion of various devices and appliances, particularly to a lip-type sealing apparatus provided with a sealing lip.
2. Description of the Related Art
There is conventionally known a lip-type seal in which a metal ring outer periphery is engaged with, and fixed to, the inner periphery of a housing, and a sealing lip supported by the metal ring slides in close contact with a shaft peripheral surface. In a lip-type sealing apparatus, it is the usual practice to cover the outer periphery of the metal ring with a stationary sealing portion made of a rubber-like elastic material so as to ensure sealing of a stationary portion over the shaft hole inner periphery of a housing.
When using a pressurized liquid for sealing, however, a stop ring is engaged with the shaft hole inner periphery of the housing, or when a bearing is arranged on the open-air side of the sealing apparatus, a bearing outer race is used for preventing coming-off.
When a stationary seal is not provided on the outer periphery of the metal ring, the open-air side end of the metal ring outer periphery certainly engages with the stop ring. When a stationary seal is provided on the metal ring outer periphery, however, there is usually produced a gap of about 1 mm between the metal ring outer periphery and the inner periphery of the sealing ring attachment hole of the housing, which reduces the size of an engagement margin with the stop ring, and this may make stopping unstable. In some cases, a deformation of the stop ring may cause inclination of the sealing apparatus, thus leading to a lower sealing property.
When coming-off is prevented by means of a bearing, it is necessary to achieve engagement with the outer race while avoiding interference with the inner race rotating with the shaft. However because there are diverse and various sizes of bearing, it may happen that the inside-diameter end position of the outer race is larger than the bore diameter of the seal attachment hole. It is therefore necessary to consider a stopper in response to a particular size of bearing.